Does glass convert light wavelength? I heard that when sunlight enters house through windows, it gets converted into longer wavelengths and gets trapped inside. 
So does the glass have anything to do with this or is this about heated materials radiation, and why does the light get trapped?
 A: Just for completeness, there are some materials that do actually convert the frequency of light. They're called optical frequency converters. These tend to work only on paired photons, and thus are transparent when you look at them, but when you shine a whole lot of one frequency on them it converts up. That allows you to do some interesting things:

In this case the green is being upconverted from the monochromatic red light.
This isn't "glass" so it's not what you're asking, but one could use it in this fashion to, say convert red photons to green on the front of a solar panel and then capture the green photons at higher energy. In theory this is more efficient than capturing the two original red ones. You could, in theory, make a window that upconverted IR to visible and thus better light the room.
A: Here's how it works. Passage through a piece of glass does not change the wavelength of light. The change occurs when the light strikes objects in the room. Absorbing light energy causes those objects to warm up, and then they begin re-radiating that heat energy at wavelengths which are in the infrared range- which do not pass easily through glass. 
A: When light enters a medium of different refractive index (different than through which it was travelling before entering into it, in your example from air to glass) it’s speed changes but frequency doesn’t change as no new light is being created and since 
Speed = frequency x wavelength
And frequency is constant, therefore, wavelength must change.
Hope it helps. 
